1. Field of the Invention
The present invention relates to a bicycle crank assembly. More particularly, the present invention relates to a bicycle crank assembly that can be mounted to a hanger of a bicycle frame.
2. Background Information
The crank of a bicycle is mounted to a crank shaft that is mounted in a freely rotatable-manner to a bottom hanger of the bicycle frame. Crank assemblies in which the right crank is fastened to the crank shaft by crimping have been known for some time (see, for example, Examined Japanese Utility Model Application Publication No. 53-1708). As used herein, the terms “left” and “right” are used to described bicycle components on the assumption that the bicycle is viewed from the rear.
In conventional crank assemblies in which the right crank is fastened to the crank shaft by crimping, the crank shaft is provided with a portion having a different diameter, such as an annular groove or protrusion, and the end part of the right crank is provided with a press-fitting hole and crimping material around the edge of the press-fitting hole. The press-fitting hole is formed such that its depth is larger than the diameter of the end part of the right crank. The right crank is crimp-fastened to the crank shaft by pressing the entire end-edge of the crimping material toward the different-diameter portion, i.e., toward the outside, in the axial direction such that the crimping material bulges radially inward around the different-diameter portion. Simultaneously, as the crimping material bulges, its radially outward-facing surface crimp-fastens the sprocket.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved bicycle crank assembly. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.